1. Field of the Invention
The present invention is related generally to the field of sterility devices for catheters and, more specifically, to flexible sheath devices for protecting the sterility of the exposed portions of indwelling catheters.
2. Description of the Prior Art
It is frequently desirable to adjust the depth of insertion of an indwelling catheter which has already been left indwelling for an extended period of time. One example of such a situation occurs when a balloon-tipped catheter inserted within the heart to measure certain heart activities becomes somehow later dislodged. This may necessitate further insertion of the catheter in order to properly relocate the heart activity sensor. In such situations it is of utmost importance that the sterility of the exposed catheter portion be maintained.
The problem of protecting the sterility of exposed portions of an indwelling catheter has been long and well known in the medical art. Thus, prior art includes several patented devices which protect sterility of the exposed portion of an indwelling catheter. An early example, U.S. Pat. No. 3,867,937 to Schwartz, discloses a protective sheath comprising a very thin plastic tubular member which is in a loose sliding fit on the outer diameter of the catheter forward of the rear hub end thereof. The protective sheath collapses as the catheter is inserted to a desired body depth, with the forward end of the sheath contacting the skin adjacent the entrance site. While this device offers the advantages of a very simple construction, it lacks an airtight seal at the forward end of the sheath. Thus, this device inherently does not prevent the catheter portion residing within the sheath from becoming contaminated by outside bacteria entering through the unsealed area between the catheter and the forward end of the sheath or from bacteria which may be present at the skin entrance site.
Two very recent patent references disclose catheter sheath devices which are intended to provide a totally enclosed or sealed environment along a length of the exposed portion of an indwelling catheter, thus permitting later adjustment of the depth of insertion without creating an unacceptable risk of infection. U.S. Pat. No. 4,327,723 to Frankenhouser discloses a shield assembly including front and rear hubs sized to permit movement of the catheter therethrough, a feed tube for connecting the front and rear hubs, and a flexible sheath connecting the front and rear hubs. The front hub is connected to the rear portion of a hollow introducer which serves to facilitate the introduction of the catheter into the body. With this device, a relatively long and rigid inner feed tube is necessary to guide the catheter through the flexible sheath portion of the assembly. The feed tube serves no further use once the catheter is introduced into the body. U.S. Pat. No. 4,327,735 to Hampson discloses a device similar to the flexible sheath assembly disclosed by Frankenhouser except that the feed tube is adapted to be removed from the assembly once it has served the purpose of guiding the catheter through the interior of the flexible sheath.
The present invention discloses a flexible sheath assembly which affords all of the advantages of a totally sealed catheter sheath assembly, as disclosed in the Frankenhouser and Hampson references, but further having a more simplified construction which eliminates the need for a relatively rigid feed tube within the flexible sheath.
Other references which may have some relevance are:
______________________________________ Patent No. Inventor ______________________________________ 4,250,881 Smith 4,235,232 Spaven et al. 4,160,450 Doherty 4,079,738 Dunn 4,037,600 Poncy 3,991,762 Radford 3,894,540 Bonner 3,825,001 Bennet 3,709,223 Macalalad et al. 3,474,786 Spademan 3,335,723 Waldman 3,185,151 Czorny 3,010,453 Doherty 2,937,643 Elliot 4,062,363 Bonner 4,029,099 Fifield 3,902,500 Dryden 3,648,704 Jackson 3,792,703 Moorhead 3,854,483 Powers 3,898,993 Taniguchi 4,006,743 Kowarski 4,000,739 Stevens ______________________________________
Accordingly, it is an object of the present invention to provide an improved flexible catheter sheath assembly for an indwelling catheter.
This and other objects of and advantages of the present invention will become more apparent in the following figures and detailed description.